Lens module

Abstract

There is provided a lens module including: a first lens having positive refractive power; a second lens having positive refractive power; a third lens having a shape in which an object-side surface thereof is concave; a fourth lens having refractive power; a fifth lens having negative refractive power; and a sixth lens having negative refractive power, having a shape in which an image-side surface thereof is concave, and having at least one point of inflection formed on the image-side surface thereof.

What is claimed is: 
     
       1. A lens module comprising:
 a first lens having positive refractive power; 
 a second lens having positive refractive power; 
 a third lens having a shape in which an object-side surface thereof is concave; 
 a fourth lens having refractive power of which an object-side surface is convex; 
 a fifth lens having negative refractive power; and 
 a sixth lens having negative refractive power, having a shape in which an image-side surface thereof is concave, and having at least one point of inflection formed on the image-side surface thereof. 
 
     
     
       2. The lens module of  claim 1 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 1:
   0.3 <f 12 /f 0.8  [Conditional Equation 1]
 
 where f 12  is a composite focal length of the first and second lenses and f indicates an overall focal length of the optical system. 
 
     
     
       3. The lens module of  claim 1 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 2:
   ( EPD /2) /f 12<0.6  [Conditional Equation 2]
 
 where EPD indicates an entrance pupil diameter and f 12  is a composite focal length of the first and second lenses. 
 
     
     
       4. The lens module of  claim 1 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 3:
     f 5 /f<− 3.0  [Conditional Equation 3]
 
 where f 5  indicates a focal length of the fifth lens and f indicates an overall focal length of the optical system. 
 
     
     
       5. The lens module of  claim 1 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 4:
   | V 1 −V 5|>25  [Conditional Equation 4]
 
 where V 1  indicates an Abbe number of the first lens, and V 5  indicates an Abbe number of the fifth lens. 
 
     
     
       6. The lens module of  claim 1 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 5:
     TTL/f< 1.4  [Conditional Equation 5]
 
 where TTL indicates a distance from an object-side surface of the first lens to an image surface. 
 
     
     
       7. The lens module of  claim 1 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 6:
   0.5< f 1 /f 2<2.2  [Conditional Equation 6]
 
 where f 1  indicates a focal length of the first lens and f 2  indicates a focal length of the second lens. 
 
     
     
       8. The lens module of  claim 1 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 7:
     BFL/f >0.15  [Conditional Equation 7]
 
 where BFL indicates a distance from the image-side surface of the sixth lens to an image surface and f indicates an overall focal length of the optical system. 
 
     
     
       9. The lens module of  claim 1 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 8:
     r 1 /f> 0.2  [Conditional Equation 8]
 
 where r 1  indicates a radius of curvature of an object-side surface of the first lens and f indicates an overall focal length of the optical system. 
 
     
     
       10. The lens module of  claim 1 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 9:
   ( r 5+ r 6)/( r 5− r 6)>( r 7+ r 8)/( r 7− r 8)  [Conditional Equation 9]
 
 where r 5  and r 6  indicate radii of curvature of the object-side surface and an image-side surface of the third lens, respectively, and r 7  and r 8  indicate radii of curvature of an object-side surface and an image-side surface of the fourth lens, respectively. 
 
     
     
       11. A lens module comprising:
 a first lens having positive refractive power; 
 a second lens having positive refractive power; 
 a third lens having negative refractive power; 
 a fourth lens having refractive power and having a shape in which an object-side surface thereof is convex; 
 a fifth lens having negative refractive power; and 
 a sixth lens having negative refractive power, having a shape in which an image-side surface thereof is concave, and having at least one point of inflection formed on the image-side surface thereof. 
 
     
     
       12. The lens module of  claim 11 , wherein the first lens has a meniscus shape in which it is convex toward an object. 
     
     
       13. The lens module of  claim 11 , wherein the second lens has a shape in which both surfaces thereof are convex. 
     
     
       14. The lens module of  claim 11 , wherein the third lens has a shape in which both surfaces thereof are concave. 
     
     
       15. The lens module of  claim 11 , wherein the fourth lens has positive refractive power. 
     
     
       16. The lens module of  claim 11 , wherein the fifth lens has a meniscus shape in which it is convex toward an image. 
     
     
       17. The lens module of  claim 11 , wherein the sixth lens has a shape in which an object-side surface thereof is convex and the image-side surface thereof is concave. 
     
     
       18. The lens module of  claim 11 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 1:
   0.3 <f 12 /f 0.8  [Conditional Equation 1]
 
 where f 12  is a composite focal length of the first and second lenses and f indicates an overall focal length of the optical system. 
 
     
     
       19. The lens module of  claim 11 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 2:
   ( EPD/ 2)/ f 12<0.6  [Conditional Equation 2]
 
 where EPD indicates an entrance pupil diameter and f 12  is a composite focal length of the first and second lenses. 
 
     
     
       20. The lens module of  claim 11 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 3:
     f 5 /f<− 3.0  [Conditional Equation 3]
 
 where f 5  indicates a focal length of the fifth lens and f indicates an overall focal length of the optical system. 
 
     
     
       21. The lens module of  claim 11 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 4:
   | V 1− V 5|>25  [Conditional Equation 4]
 
 where V 1  indicates an Abbe number of the first lens, and V 5  indicates an Abbe number of the fifth lens. 
 
     
     
       22. The lens module of  claim 11 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 5:
     TTL/f< 1.4  [Conditional Equation 5]
 
 where TTL indicates a distance from an object-side surface of the first lens to an image surface. 
 
     
     
       23. The lens module of  claim 11 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 6:
   0.5< f 1 /f 2<2.2  [Conditional Equation 6]
 
 where f 1  indicates a focal length of the first lens and f 2  indicates a focal length of the second lens. 
 
     
     
       24. The lens module of  claim 11 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 7:
     BFL/f> 0.15  [Conditional Equation 7]
 
 where BFL indicates a distance from the image-side surface of the sixth lens to an image surface and f indicates an overall focal length of the optical system. 
 
     
     
       25. The lens module of  claim 11 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 8:
     r 1/ f> 0.2  [Conditional Equation 8]
 
 where r 1  indicates a radius of curvature of an object-side surface of the first lens and f indicates an overall focal length of the optical system. 
 
     
     
       26. The lens module of  claim 11 , wherein an optical system including the first to sixth lenses satisfies Conditional Equation 9:
   ( r 5+ r 6)/( r 5− r 6)>( r 7+ r 8)/( r 7− r 8)  [Conditional Equation 9]
 
 where r 5  and r 6  indicate radii of curvature of an object-side surface and an image-side surface of the third lens, respectively, and r 7  and r 8  indicate radii of curvature of the object-side surface and an image-side surface of the fourth lens, respectively.